Elegant CSS animations are actually rare: I have to pick carefully what to animate on each element, most of the time, the first attempts are not as smooth or subtle as expected. z-index, background-image, gradients, border-styles and many more properties can’t be animated. I have to compose with what remains with care.
Conclusion: the work is really about transitions. All the constraints I chose (or not chose) to adopt, allow me to focus on the transitional states of the composition. It’s a bit more hard that I expected, but I am happy this way. Also, I am writing about it, I guess it’s a good sign.